In currently commercially available vacuum insulation panels, inorganic compounds, such as glass wool, fumed silica, aerogel and the like, are used as a core. In addition, nylon/PET/aluminum foil, or an aluminum deposition layer and a welding layer such as PE, PP and the like are used for a shell. Further, to secure long term performance, vacuum insulation panels include a getter such as quicklime (CaO), zeolite and the like, a moisture absorbent such as silica gel and the like, and metal powder.
However, since maintenance of an internal vacuum level is the most important factor in performance of the vacuum insulation panels, the internal vacuum level is maintained by sealing the shell at a high vacuum of 10 Pa or less. However, since an unwelded portion such as an edge of the shell is vulnerable to physical impact and thus is likely to rupture, there is difficulty handling of the vacuum insulation panel.
Korean Patent No. 10-0775716 discloses a vacuum insulation panel that is composed of a core, a getter and a shell, and has a through-hole formed therein, wherein a thermal welding portion is formed according to the core and a surrounding edge around the core is disposed as the thermal welding portion, thereby maintaining a large effective heat insulating area. However, this patent does not disclose improvement in a welding ratio of the thermal welding portion by welding an unwelded portion of the shell, such as an edge of the shell, and the like.